Electric heating – Metal heating – By arc
Patent
1993-06-14
1995-12-19
Paschall, Mark H.
Electric heating
Metal heating
By arc
21912185, 2191216, 445 7, B23K 2600, H01Y 2102
Patent
active
054770220
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an electrical-discharge electrode, in particular spark-plug electrodes, having a main electrode body made of metal and a method of producing it.
Contemporary spark plugs have, as a rule, a central electrode and an earth electrode, the tips of the two electrodes being arranged with respect to one another in such a way that a spark gap is left free. The tips are subject to an appreciable wear as a result of the continuous spark production between the two electrodes. This problem imposes strict requirements on the high-temperature resistance, corrosion resistance and thermal expansion characteristics of the electrode tip. Spark erosion and oxidation phenomena also result in an appreciable stress.
In order to improve, in particular, the electrode tip, U.S. Patent Specification 4 540 910 therefore proposes, for example, that an interlayer which serves to compensate for the markedly different thermal expansion behaviour of electrodes and metal coatings is disposed between the metal electrode, which is composed of a nickel alloy, and a metal layer with high wear resistance, which is made of a platinum-containing alloy. This interlayer is composed of an alloy which is made up of a platinum alloy and nickel. To apply the wear-resistant metal layer to the metal electrode, the wear-resistant metal layer is first mechanically bonded to the interlayer and then the interlayer provided with the metal layer is joined to the metal electrode by resistance welding. The production expenditure necessary for this purpose and, in particular, the high material costs are appreciable, and furthermore, only the thermal expansion behaviour is improved.
German Patent Specification 31 32 814 furthermore discloses that a platelet made of noble metal, such as, for example, platinum, is applied by resistance welding to the free end face of a central electrode of a sparking plug. In the case of this central electrode, however, the problem then arises that the noble-metal platelet peels away from the central electrode as a result of stresses in the joint zone under fairly high thermal and corrosive loads. Here, again, even the material costs are appreciable.
SUMMARY OF THE INVENTION
The present invention comprising an electrical-discharge electrode having a main electrode body made of metal which is provided with an intermetallic phase in at least the region of its tip and in which the intermetallic phase is composed of nickel aluminide, and the method for producing these electrical discharge electrodes, makes use of the advantages of the known IP (intermetallic-phase) materials. Intermetallic phases are understood as meaning compounds of metals with ordered atomic distributions. These intermetallic phases are stronger than metal alloys and more oxidation-resistant than non-noble-metal alloys and more deformable than ceramic, even at high temperatures. Their properties are therefore between those of metal and ceramic.
For more detailed explanation of the intermetallic phases, references is made to "Magazin Neue Werkstoffe 1/89", pages 15 et seq. and to the article entitled "Advances in Intermetallics" in Advanced Material & Processes 2/89. Intermetallic phases are, for example, titanium aluminides and nickel aluminides.
The electrode may be composed completely of the IP material or carry a tip made of IP material on an electrode body made of otherwise standard electrode material.
Method of producing an electrode according to the invention vary. With regard to the application of the IP-material electrode tip, there are two possible methods within the scope of the present invention. On the one hand, an IP material, i.e. an intermetallic phase itself, can be applied to the main electrode body. In this connection, nickel aluminides, such as, for example NiAl.sub.3, Ni.sub.2 Al.sub.3 or the like, are suitable. The join to the main electrode body is then made by known methods, such as welding or high-temperature soldering.
A further advantageous possible method is, however, to apply a mater
REFERENCES:
patent: 4175144 (1979-11-01), Hori et al.
patent: 4540910 (1985-09-01), Kondo et al.
patent: 4904216 (1990-02-01), Kagawa et al.
patent: 4963112 (1990-10-01), Benedikt et al.
patent: 5093879 (1992-03-01), Bregman et al.
patent: 5102700 (1992-04-01), Baldi
"Nickel-Aluminum-eine neue leichte Super-Legierung", Magazin Neue Werkstoffe, Apr. 1989, p. 14.
James D. Destefani, "Advances in Inter-metallics", Advanced Materials & Processes, Feb. 1989, pp. 37-41.
Paschall Mark H.
Robert & Bosch GmbH
LandOfFree
Electrode and process for manufacturing it does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrode and process for manufacturing it, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrode and process for manufacturing it will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-993208